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Total 47 records

    Fast-swelling superabsorbent hydrogels from poly(2-hydroxy ethyl acrylate-co-sodium acrylate) grafted on starch

    , Article Starch/Staerke ; Volume 60, Issue 2 , 2008 , Pages 79-86 ; 00389056 (ISSN) Pourjavadi, A ; Samadi, M ; Ghasemzadeh, H ; Sharif University of Technology
    2008
    Abstract
    Fast-swelling highly porous superabsorbent hydrogels were synthesized through a rapid radical polymerization under normal atmospheric conditions. To synthesize a biopolymer-based superabsorbent hydrogel, 2-hydroxyethyl acrylate (HEA) and sodium acrylate (AANa) were grafted on the starch backbone in an aqueous solution. The graft copolymerization reaction was carried out in the presence of ammonium persulfate (APS) as an initiator and N, N′-methylenebisacrylamide (MBA) as a cross-linker in a homogeneous medium. The chemical structure of the hydrogels was confirmed by FT-IR spectroscopy and thermogravimetric analysis (TGA). The morphology of the samples was examined by scanning electron... 

    Modified CMC. 4. Ceric-initiated methacrylonitrile graft polymerization onto carboxymethylcellulose

    , Article Journal of Polymer Materials ; Volume 21, Issue 4s , 2004 , Pages 351-359 ; 09738622 (ISSN) Pourjavadi, A ; Zohuriaan Mehr, M. J ; Pooraghaberar, A ; Hosseinzadeh, H ; Sharif University of Technology
    2004
    Abstract
    Graft copolymerization of methacrylonitrile (MAN) onto carboxymethylcellulose (CMC) was carried out under argon atmosphere in a homogeneous aqueous medium by using ceric ammonium nitrate (CAN) as an initiator. The FTIR spectroscopy and solubility characteristics of the products were used for confirming the graft copolymer formation. The effect of the concentration of the initiator, monomer and polysaccharide as well as the reaction time and temperature on the graft copolymerization reactions were investigated to achieve the optimum grafting conditions (i.e. CAN 0.00065 mol/L, MAN 0.85 mol/L, CMC 1% W/V, reaction temperature 45°C, and reaction time 2 h). According to the empirical rates of... 

    Modified carrageenan 3. Synthesis of a novel polysaccharide-based superabsorbent hydrogel via graft copolymerization of acrylic acid onto kappa-carrageenan in air

    , Article European Polymer Journal ; Volume 40, Issue 7 , 2004 , Pages 1363-1370 ; 00143057 (ISSN) Pourjavadi, A ; Harzandi, A. M ; Hosseinzadeh, H ; Sharif University of Technology
    2004
    Abstract
    A novel biopolymer-based superabsorbent hydrogel was synthesized through chemically crosslinking graft copolymerization of acrylic acid (AA) onto kappa-carrageenan (κC), in the presence of a crosslinking agent and a free radical initiator. A proposed mechanism for κC-g-polyacrylic acid was suggested and the affecting variables onto graft polymerization (i.e. the crosslinker, the monomer and the initiator concentration, the neutralization percent and reaction temperature) were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. Maximum water absorbency of the optimized final product was found to be 789 g/g. The swelling capacity of the synthesized... 

    Chitosan-g-poly(acrylic acid)/kaolin superabsorbent composite: Synthesis and characterization

    , Article Polymers and Polymer Composites ; Volume 14, Issue 2 , 2006 , Pages 203-211 ; 09673911 (ISSN) Pourjavadi, A ; Mahdavinia, G. R ; Sharif University of Technology
    Rapra Technology Ltd  2006
    Abstract
    A novel superabsorbent composite based on chitosan was prepared by graft copolymerization of acrylic acid (AA) in the presence of kaolin powder using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The synthetic variables (i.e. AA, MBA, and APS concentration, and the kaolin amount) affecting the water absorbency of the resulting superabsorbent composite were studied. Evidence of grafting and kaolin interaction was obtained by comparing the FTIR spectra of the initial substrates with that of the superabsorbent composite. A new absorption band at 1722 cm-1 in the composite spectrum confirmed the kaolin-organic polymer linkage. The effect of... 

    Modified CMC: Part1-optimized synthesis of carboxymethyl cellulose-g-polyacrylonitrile

    , Article Iranian Polymer Journal (English Edition) ; Volume 14, Issue 2 , 2005 , Pages 131-138 ; 10261265 (ISSN) Zohuriaan Mehr, M. J ; Pourjavadi, A ; Sadeghi, M ; Sharif University of Technology
    2005
    Abstract
    As the first part of a continued research on conversion of carboxymethyl cellulose-sodium salt (CMC) to useful biopolymer-based materials, large numbers of cyanide functional groups were introduced onto CMC by grafting with polyacrylonitrile (PAN). The graft copolymerization reactions were carried out under nitrogen atmosphere using ceric ammonium nitrate (CAN) as an initiator. Evidence of grafting was obtained by comparing FTIR spectra of CMC and the graft copolymer as well as solubility characteristics of the products. The synthetic conditions were systematically optimized through studying the effective factors including temperature and concentrations of initiator, acrylonitrile monomer,... 

    Multi Variable Generalized Predictive Control of a Solution Copolymerization Reaction

    , M.Sc. Thesis Sharif University of Technology Ghaffarian, Shahab (Author) ; Pishvaie, Mahmoud Reza (Supervisor)
    Abstract
    Continuous synthesis of different kinds of industrial copolymers plays an important role in economics of the polymer industry. But copolymerization reactions are complex and with a high degree of nonlinearity so the control problem in this case needs a detailed study on system dynamic behavior. One of the solutions is using a optimal control method in the shape of predictive controllers. The main goal in this thesis is to design a generalized multi-varriable predictive controller for a solution copolymerization of methyl methacrylate and vinyl acetate in a continuous stirred tank reactor with separator and recycle stream. In this study, after simulating the nonlinear model of the process... 

    Carrageenan-g-poly(acrylamide)/poly(vinylsulfonic acid, sodium salt) as a novel semi-IPN hydrogel: Synthesis, characterization, and swelling behavior

    , Article Polymer Engineering and Science ; Volume 47, Issue 9 , 2007 , Pages 1388-1395 ; 00323888 (ISSN) Pourjavadi, A ; Ghasemzadeh, H ; Sharif University of Technology
    2007
    Abstract
    A semi-interpenetrating polymer network (semi-IPN) hydrogel based on kappa-carrageenan (κC) and poly (vinylsulfonic acid, sodium salt) (PVSA) was prepared by graft copolymerization of acrylamide (AAm) using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. FTIR spectroscopy was used for confirming the structure of the final product. It was found that the chemical composition of the Semi-IPN hydrogel is equal to the initial homopolymers and monomer feed compositions. The swelling capacity of the hydrogel was shown to be affected by the MBA, APS, and AAm concentration as well as κC/PVSA weight ratio. The swelling behavior of the hydrogel was... 

    Synthesis, characterization and swelling behavior of gelatin-g-poly(sodium acrylate)/kaolin superabsorbent hydrogel composites

    , Article Journal of Composite Materials ; Volume 41, Issue 17 , 2007 , Pages 2057-2069 ; 00219983 (ISSN) Pourjavadi, A ; Hosseinzadeh, H ; Sadeghi, M ; Sharif University of Technology
    2007
    Abstract
    In the present paper, a novel superabsorbent hydrogel composite based on gelatin have been prepared via graft copolymerization of acrylic acid (AA) in the presence of kaolin powder using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. Certain variables of the graft copolymerization (i.e., the monomer, the initiator, and the crosslinker concentration as well as kaolin/gelatin weight ratio) affected on the ultimate water-swelling capacity were optimized. The composite structure was confirmed using Fourier transform infrared (FTIR) spectroscopy. A new absorption band at 1728 cm1 in the composite spectrum confirmed kaolinorganic polymer... 

    Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked ΚC-g-AMPS superabsorbent hydrogel with antisalt and pH-responsiveness properties

    , Article Journal of Applied Polymer Science ; Volume 98, Issue 1 , 2005 , Pages 255-263 ; 00218995 (ISSN) Pourjavadi, A ; Hosseinzadeh, H ; Mazidi, R ; Sharif University of Technology
    2005
    Abstract
    To synthesize a novel biopolymer-based superabsorbent hydrogel, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was grafted onto kappa-carrageenan (ΚC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N′,N′-tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N′-methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for ΚC-g-AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature,... 

    Hydrolyzed Protein-Based Highly Porous Hydrogels: Synthesis and Characteristics

    , Ph.D. Dissertation Sharif University of Technology Kurdtabar, Mehran (Author) ; Pourjavadi, Ali (Supervisor)
    Abstract
    This thesis focuses on the preparation and super-swelling behavior of four highly porous hydrogels: 1. Firstly, we have developed a collagen-based highly porous hydrogel by neutralizing the grafted poly(acrylamide-co-acrylic acid) after gel formation. Systematically, the certain variables of the graft copolymerization were optimized to achieve maximum swelling capacity. Morphology of the samples was examined by scanning electron microscopy (SEM) and was shown the pores were induced into the hydrogel by water evaporation resulting from neutralization process. The absorbency under load (AUL) and centrifuge retention capacity (CRC) were measured. The synthesized hydrogel exhibited a... 

    Preparation and Property Investigation of Propylene- Ethylene Copolymer Graphene Nano Composites

    , M.Sc. Thesis Sharif University of Technology Torabi, Hooman (Author) ; Ramezani Saadatabadi, Ahmad (Supervisor)
    Abstract
    In this research, polypropylene and propylene- ethylene copolymers were synthesized and propylene- ethylene copolymer Graphene Oxide Nano composites were prepared via solution mixing method. Nano Graphene Oxide sheets were synthesized utilizing modified hummer’s method. Ziegler Natta catalyst system was a complex of Magnesium Ethoxide as the support of the catalyst and Titanium tetra Chloride as the catalyst. Tri iso Butyl Aluminum (TiBA) and Tri Ethyl Aluminum (TEAl) were used as co catalyst. FT-IR and XRD patterns show well oxidation of graphite sheets and fragmentations of them. FESEM images clear the successfulness of copolymerization and also well-dispersion and distribution of Nano... 

    Synthesis, characterization, and swelling behavior of alginate-g- poly(sodium acrylate)/kaolin superabsorbent hydrogel composites

    , Article Journal of Applied Polymer Science ; Volume 105, Issue 5 , 2007 , Pages 2631-2639 ; 00218995 (ISSN) Pourjavadi, A ; Ghasemzadeh, H ; Soleyman, R ; Sharif University of Technology
    2007
    Abstract
    A novel superabsorbent composite based on sodium alginate and the inorganic clay kaolin was synthesized via the graft copolymerization of acrylic acid (AA) in an aqueous medium with methylene bisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The effects of reaction variables, such as the MBA, AA, and APS concentrations and the alginate/kaolin weight ratio, on the water absorbency of the composite were systematically optimized. Evidence of grafting and kaolin interactions was obtained by a comparison of the Fourier transform infrared spectra of the initial substrates with that of the superabsorbent composite, and the hydrogel structure was confirmed... 

    Synthesis and absorbency of gelatin-graft-poly(sodium acrylate-co- acrylamide) superabsorbent hydrogel with saltand pH-responsiveness properties

    , Article E-Polymers ; 2006 , Pages 1-15 ; 16187229 (ISSN) Pourjavadi, A ; Sadeghi, M ; Mahmodi Hashemi, M ; Hosseinzadeh, H ; Sharif University of Technology
    European Polymer Federation  2006
    Abstract
    In this article, we synthesize a novel gelatin-based superabsorbent hydrogel via graft copolymerization of mixtures of acrylic acid (AA) and acrylamide (AAm) onto gelatin backbones. The polymerization reaction was carried out in an aqueous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N-methylene bisacrylamide (MBA) as a crosslinker. The hydrogel structures were confirmed by FTIR spectroscopy. The effect of grafting variables, i.e. concentration of MBA and APS, AA/AAm weight ratio, and reaction time and temperature, was systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The swelling behavior of these absorbent polymers... 

    Optimization of synthetic conditions of a novel collagen-based superabsorbent hydrogel by Taguchi method and investigation of its metal ions adsorption

    , Article Journal of Applied Polymer Science ; Volume 102, Issue 5 , 2006 , Pages 4878-4885 ; 00218995 (ISSN) Pourjavadi, A ; Salimi, H ; Amini Fazl, M. S ; Kurdtabar, M ; Amini Fazl, A. R ; Sharif University of Technology
    2006
    Abstract
    A novel biopolymer-based superabsorbent hydrogel was synthesized through chemical crosslinking by graft copolymerization of partially neutralized acrylic acid onto the hydrolyzed collagen, in the presence of a crosslinking agent and a free radical initiator. The Taguchi method, a robust experimental design, was employed for the optimization of the synthesis reaction based on the swelling capacity of the hydrogels. This method was applied for the experiments and standard L16 orthogonal array with three factors and four levels were chosen. The critical parameters that have been selected for this study are crosslinker (N,N′-methylene bisacrylamide), initiator (potassium persulfate), and monomer... 

    The effects of reaction conditions on block copolymerization of chitosan and poly(ethylene glycol)

    , Article Carbohydrate Polymers ; Volume 81, Issue 4 , July , 2010 , Pages 799-804 ; 01448617 (ISSN) Ganji, F ; Abdekhodaie, M. J ; Sharif University of Technology
    2010
    Abstract
    A novel injectable in situ gelling thermosensitive chitosan-block-poly(ethylene glycol) formulation was synthesized for drug delivery applications. Block copolymerization of monomethoxy-poly(ethylene glycol) onto chitosan using potassium persulfate as an initiator was carried under a nitrogen atmosphere in aqueous solution. The effects of potassium persulfate and poly(ethylene glycol) concentrations, reaction time and reaction temperature on block polymerization were studied by determining the yield of reaction (%Y), polymerization efficiency (%E) and add-on percentage (%Add-on). Keeping the other conditions constant, the optimum reaction conditions were found to be initiator = 0.01 M,... 

    Acidic derivatives of melamine as template in copolymerization of aniline and metanilic acid

    , Article Polymer - Plastics Technology and Engineering ; 2017 , Pages 1-10 ; 03602559 (ISSN) Khodadadi, F ; Najafi Moghadam, P ; Hashemi, M. M ; Sharif University of Technology
    Abstract
    In this paper, new polymer composites were synthesized by template copolymerization of aniline and metanilic acid in the presence of prepared melamine triacetic acid and poly(melamine-co-citric acid) as polyacids and dopants. The properties of the poly(aniline-co-metanilic acid) composites were studied by Fourier transform infrared, X-ray diffraction, scanning electron microscope, CV, and differential scanning calorimeter analysis. The four-point probe technique was used for evaluating the electrical conductivity of the composites. The scanning electron micrographs disclosed that the products had the morphology with agglomerated distorted spherical shapes with the average size of 40–50 nm.... 

    High-performance carboxylate superplasticizers for concretes: Interplay between the polymerization temperature and properties

    , Article Journal of Applied Polymer Science ; Volume 134, Issue 23 , 2017 ; 00218995 (ISSN) Tajbakhshian, A ; Saeb, M. R ; Jafari, S. H ; Najafi, F ; Khonakdar, H. A ; Ayoubi, M ; Hassanpour Asl, F ; Sharif University of Technology
    Abstract
    Polycarboxylate superplasticizers based on acrylic acid (AA) and maleic anhydride (MAn) were synthesized via free-radical copolymerization with an ethylene glycol monomer and characterized. The copolymerization temperature (ranging from 50 to 90 °C) appeared to be the key operating factor governing the chemical structure of the superplasticizers. The chemical structures of the products were analyzed by gel permeation chromatography, whereas an optimized sample was further analyzed by Fourier transform infrared spectroscopy and 1H-NMR. Superplasticizers of the AA and MAn classes were then incorporated into concrete, and their performances were measured by slump and slump loss tests, where a... 

    Acidic derivatives of melamine as template in copolymerization of aniline and metanilic acid

    , Article Polymer - Plastics Technology and Engineering ; Volume 57, Issue 10 , 2018 , Pages 965-974 ; 03602559 (ISSN) Khodadadi, F ; Najafi Moghadam, P ; Hashemi, M. M ; Sharif University of Technology
    Taylor and Francis Inc  2018
    Abstract
    In this paper, new polymer composites were synthesized by template copolymerization of aniline and metanilic acid in the presence of prepared melamine triacetic acid and poly(melamine-co-citric acid) as polyacids and dopants. The properties of the poly(aniline-co-metanilic acid) composites were studied by Fourier transform infrared, X-ray diffraction, scanning electron microscope, CV, and differential scanning calorimeter analysis. The four-point probe technique was used for evaluating the electrical conductivity of the composites. The scanning electron micrographs disclosed that the products had the morphology with agglomerated distorted spherical shapes with the average size of 40–50 nm.... 

    Irradiation synthesis of biopolymer-based superabsorbent hydrogel: optimization using the taguchi method and investigation of its swelling behavior

    , Article Advances in Polymer Technology ; Volume 28, Issue 2 , 2009 , Pages 131-140 ; 07306679 (ISSN) Rezanejade Bardajee, G ; Pourjavadi, A ; Soleyman, R ; Sharif University of Technology
    2009
    Abstract
    In this report, the synthesis of a novel superabsorbent hydrogel via γ-irradiation graft copolymerization of acrylamide onto sodium alginate and kappa-carrageenan hybrid backbones in a homogeneous solution is described. The Taguchi method was used as a powerful experimental design tool for synthesis optimization. A series of superabsorbent hydrogels was synthesized by proposed conditions of Qualitek-4 software. Considering the results of nine trials according to analysis of variance, optimum conditions were proposed. The swelling behavior of optimum superabsorbent hydrogels was studied in various solutions, with pH values ranging from 1 to 13. In addition, swelling kinetics, swelling in... 

    Synthesis and swelling behavior of a new superabsorbent hydrogel network based on polyacrylamide grafted onto salep

    , Article Journal of Applied Polymer Science ; Volume 112, Issue 5 , 2009 , Pages 2625-2633 ; 00218995 (ISSN) Pourjavadi, A ; Rezanejade Bardajee, G ; Soleyman, R ; Sharif University of Technology
    2009
    Abstract
    Synthesis and swelling behavior of a new superabsorbent hydrogel based on natural salep grafted with Polyacrylamide is described. The new superabsorbent hydrogel biopolymer was synthesized via radical crosslink-ing and graft copolymerization of acrylamide monomer onto salep backbones. Regarding to the water absorption of hydrogel, the best synthesis condition is reported. FTIR spectroscopy and thermogravimetric analysis were used to confirm the structure of the final product and a mechanism for superabsorbent hydrogel formation was also suggested. After preparing the desired hydrogels based on optimum condition, several factors affecting the swelling behavior of hydrogel including pH of...